图片预加载之模拟img.load()

function imgBatchLoad()
{
    var instance = this;
    this.loadCount = 0;
    this.images = [];
    this.imgCount = 0;
    this.progress = 0;
    this.load = function(pathArray)
    {
        instance.imgCount = pathArray.length;
        for(var i=0;i<pathArray.length;i++)
        {
            var imgDom = new Image();
            imgDom.src = pathArray[i];
            imgDom.onload = updateProgress(imgDom,i);
        }
    };
    this.onload = function()
    {

    };
    this.onProgress = function()
    {

    };
    function updateProgress(img,index)
    {
        return function(){
            instance.loadCount++;
            instance.images[index] = img;
            instance.progress = instance.loadCount / instance.imgCount*100;
            instance.onProgress(instance.progress);
            if(instance.loadCount == instance.imgCount)
            {
                instance.onload(instance.images);
            }

        }
    }
}